re PR fortran/35810 ([TR 15581 / F2003] Automatic reallocation on assignment to allocatable variables)

2010-11-28  Paul Thomas  <pault@gcc.gnu.org>

	 PR fortran/35810
	* trans-array.c (gfc_trans_array_constructor): If the loop->to
	is a VAR_DECL, assume this is dynamic. In this case, use the
	counter to obtain the value and set loop->to appropriately.
	(gfc_conv_ss_descriptor): Always save the offset of a variable
	in info.saved_offset.
	(gfc_conv_ss_startstride): Do not attempt bound checking of the
	lhs of an assignment, if allocatable and f2003 is allowed.
	(gfc_conv_loop_setup): If possible, do not use an allocatable
	lhs variable for the loopspec.
	(gfc_is_reallocatable_lhs): New function.
	(get_std_lbound): New function.
	(gfc_alloc_allocatable_for_assignment): New function.
	* gfortran.h : Add flag_realloc_lhs to the options structure.
	* lang.opt : Add option f(no-)realloc-lhs.
	* invoke.texi : Document option f(no-)realloc-lhs.
	* options.c (gfc_init_options, gfc_post_options,
	gfc_handle_option): Incorporate f(no-)realloc-lhs with default
	to frealloc_lhs for -std > f95.
	* trans-array.h : Add primitive for previous.
	* trans-expr.c (gfc_conv_string_length): Return if character
	length is a variable and the expression is NULL.
	(gfc_conv_procedure_call): If the call is of the kind x = f(...)
	and the lhs is allocatable and reallocation on assignment OK,
	call gfc_alloc_allocatable_for_assignment. Do not generate the
	function call unless direct by reference.
	(realloc_lhs_loop_for_fcn_call): New function.
	(realloc_lhs_bounds_for_intrinsic_call): New function.
	(gfc_trans_arrayfunc_assign): Reallocation assignments need
	a loopinfo and for the loop bounds to be set.  With intrinsic
	functions, free the lhs data and let the library allocate the
	data array. Done by the new functions above.
	(gfc_trans_assignment_1): If the lhs is allocatable and
	reallocation on assignment is allowed, mark the lhs and use
	gfc_alloc_allocatable_for_assignment to make the reallocation.
	* trans.h : Add is_alloc_lhs bitfield to gfc_ss structure.

2010-11-28  Paul Thomas  <pault@gcc.gnu.org

	PR fortran/35810
	* gfortran.dg/realloc_on_assign_1.f03: New test.
	* gfortran.dg/realloc_on_assign_2.f03: New test.
	* gfortran.dg/transpose_2.f90: dg-option -fno-realloc-lhs.
	* gfortran.dg/unpack_bounds_1.f90: The same.
	* gfortran.dg/cshift_bounds_2.f90: The same.
	* gfortran.dg/matmul_bounds_2.f90: The same.
	* gfortran.dg/matmul_bounds_3.f90: The same.
	* gfortran.dg/matmul_bounds_4.f90: The same.
	* gfortran.dg/matmul_bounds_5.f90: The same.

From-SVN: r167220

1 files changed, 166 insertions, 3 deletions

diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c
index 3401ae9..5857c0d 100644
--- a/gcc/fortran/trans-expr.c
+++ b/gcc/fortran/trans-expr.c
@@ -335,6 +335,11 @@ gfc_conv_string_length (gfc_charlen * cl, gfc_expr * expr, stmtblock_t * pblock)
 
   gfc_init_se (&se, NULL);
 
+  if (!cl->length
+	&& cl->backend_decl
+	&& TREE_CODE (cl->backend_decl) == VAR_DECL)
+    return;
+
   /* If cl->length is NULL, use gfc_conv_expr to obtain the string length but
      "flatten" array constructors by taking their first element; all elements
      should be the same length or a cl->length should be present.  */
@@ -342,7 +347,6 @@ gfc_conv_string_length (gfc_charlen * cl, gfc_expr * expr, stmtblock_t * pblock)
     {
       gfc_expr* expr_flat;
       gcc_assert (expr);
-
       expr_flat = gfc_copy_expr (expr);
       flatten_array_ctors_without_strlen (expr_flat);
       gfc_resolve_expr (expr_flat);
@@ -3355,8 +3359,30 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
 	    se->expr = build_fold_indirect_ref_loc (input_location,
 						se->expr);
 
-	  result = build_fold_indirect_ref_loc (input_location,
-						se->expr);
+	  /* If the lhs of an assignment x = f(..) is allocatable and
+	     f2003 is allowed, we must do the automatic reallocation.
+	     TODO - deal with instrinsics, without using a temporary.  */
+	  if (gfc_option.flag_realloc_lhs
+		&& se->ss && se->ss->loop_chain
+		&& se->ss->loop_chain->is_alloc_lhs
+		&& !expr->value.function.isym
+		&& sym->result->as != NULL)
+	    {
+	      /* Evaluate the bounds of the result, if known.  */
+	      gfc_set_loop_bounds_from_array_spec (&mapping, se,
+						   sym->result->as);
+
+	      /* Perform the automatic reallocation.  */
+	      tmp = gfc_alloc_allocatable_for_assignment (se->loop,
+							  expr, NULL);
+	      gfc_add_expr_to_block (&se->pre, tmp);
+
+	      /* Pass the temporary as the first argument.  */
+	      result = info->descriptor;
+	    }
+	  else
+	    result = build_fold_indirect_ref_loc (input_location,
+						  se->expr);
 	  VEC_safe_push (tree, gc, retargs, se->expr);
 	}
       else if (comp && comp->attr.dimension)
@@ -3370,6 +3396,17 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
 	  /* Evaluate the bounds of the result, if known.  */
 	  gfc_set_loop_bounds_from_array_spec (&mapping, se, comp->as);
 
+	  /* If the lhs of an assignment x = f(..) is allocatable and
+	     f2003 is allowed, we must not generate the function call
+	     here but should just send back the results of the mapping.
+	     This is signalled by the function ss being flagged.  */
+	  if (gfc_option.flag_realloc_lhs
+		&& se->ss && se->ss->is_alloc_lhs)
+	    {
+	      gfc_free_interface_mapping (&mapping);
+	      return has_alternate_specifier;
+	    }
+
 	  /* Create a temporary to store the result.  In case the function
 	     returns a pointer, the temporary will be a shallow copy and
 	     mustn't be deallocated.  */
@@ -3394,6 +3431,17 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
 	  /* Evaluate the bounds of the result, if known.  */
 	  gfc_set_loop_bounds_from_array_spec (&mapping, se, sym->result->as);
 
+	  /* If the lhs of an assignment x = f(..) is allocatable and
+	     f2003 is allowed, we must not generate the function call
+	     here but should just send back the results of the mapping.
+	     This is signalled by the function ss being flagged.  */
+	  if (gfc_option.flag_realloc_lhs
+		&& se->ss && se->ss->is_alloc_lhs)
+	    {
+	      gfc_free_interface_mapping (&mapping);
+	      return has_alternate_specifier;
+	    }
+
 	  /* Create a temporary to store the result.  In case the function
 	     returns a pointer, the temporary will be a shallow copy and
 	     mustn't be deallocated.  */
@@ -5331,6 +5379,81 @@ arrayfunc_assign_needs_temporary (gfc_expr * expr1, gfc_expr * expr2)
 }
 
 
+/* Provide the loop info so that the lhs descriptor can be built for
+   reallocatable assignments from extrinsic function calls.  */
+
+static void
+realloc_lhs_loop_for_fcn_call (gfc_se *se, locus *where, gfc_ss **ss)
+{
+  gfc_loopinfo loop;
+  /* Signal that the function call should not be made by
+     gfc_conv_loop_setup. */
+  se->ss->is_alloc_lhs = 1;
+  gfc_init_loopinfo (&loop);
+  gfc_add_ss_to_loop (&loop, *ss);
+  gfc_add_ss_to_loop (&loop, se->ss);
+  gfc_conv_ss_startstride (&loop);
+  gfc_conv_loop_setup (&loop, where);
+  gfc_copy_loopinfo_to_se (se, &loop);
+  gfc_add_block_to_block (&se->pre, &loop.pre);
+  gfc_add_block_to_block (&se->pre, &loop.post);
+  se->ss->is_alloc_lhs = 0;
+}
+
+
+static void
+realloc_lhs_bounds_for_intrinsic_call (gfc_se *se, int rank)
+{
+  tree desc;
+  tree tmp;
+  tree offset;
+  int n;
+
+  /* Use the allocation done by the library.  */
+  desc = build_fold_indirect_ref_loc (input_location, se->expr);
+  tmp = gfc_conv_descriptor_data_get (desc);
+  tmp = gfc_call_free (fold_convert (pvoid_type_node, tmp));
+  gfc_add_expr_to_block (&se->pre, tmp);
+  gfc_conv_descriptor_data_set (&se->pre, desc, null_pointer_node);
+  /* Unallocated, the descriptor does not have a dtype.  */
+  tmp = gfc_conv_descriptor_dtype (desc);
+  gfc_add_modify (&se->pre, tmp, gfc_get_dtype (TREE_TYPE (desc)));
+
+  offset = gfc_index_zero_node;
+  tmp = gfc_index_one_node;
+  /* Now reset the bounds from zero based to unity based.  */
+  for (n = 0 ; n < rank; n++)
+    {
+      /* Accumulate the offset.  */
+      offset = fold_build2_loc (input_location, MINUS_EXPR,
+				gfc_array_index_type,
+				offset, tmp);
+      /* Now do the bounds.  */
+      gfc_conv_descriptor_offset_set (&se->post, desc, tmp);
+      tmp = gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[n]);
+      tmp = fold_build2_loc (input_location, PLUS_EXPR,
+			     gfc_array_index_type,
+			     tmp, gfc_index_one_node);
+      gfc_conv_descriptor_lbound_set (&se->post, desc,
+				      gfc_rank_cst[n],
+				      gfc_index_one_node);
+      gfc_conv_descriptor_ubound_set (&se->post, desc,
+				      gfc_rank_cst[n], tmp);
+
+      /* The extent for the next contribution to offset.  */
+      tmp = fold_build2_loc (input_location, MINUS_EXPR,
+			     gfc_array_index_type,
+			     gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[n]),
+			     gfc_conv_descriptor_lbound_get (desc, gfc_rank_cst[n]));
+      tmp = fold_build2_loc (input_location, PLUS_EXPR,
+			     gfc_array_index_type,
+			     tmp, gfc_index_one_node);
+    }
+  gfc_conv_descriptor_offset_set (&se->post, desc, offset);
+}
+
+
+
 /* Try to translate array(:) = func (...), where func is a transformational
    array function, without using a temporary.  Returns NULL if this isn't the
    case.  */
@@ -5373,6 +5496,31 @@ gfc_trans_arrayfunc_assign (gfc_expr * expr1, gfc_expr * expr2)
   se.direct_byref = 1;
   se.ss = gfc_walk_expr (expr2);
   gcc_assert (se.ss != gfc_ss_terminator);
+
+  /* Reallocate on assignment needs the loopinfo for extrinsic functions.
+     This is signalled to gfc_conv_procedure_call by setting is_alloc_lhs.
+     Clearly, this cannot be done for an allocatable function result, since
+     the shape of the result is unknown and, in any case, the function must
+     correctly take care of the reallocation internally. For intrinsic
+     calls, the array data is freed and the library takes care of allocation.
+     TODO: Add logic of trans-array.c: gfc_alloc_allocatable_for_assignment
+     to the library.  */    
+  if (gfc_option.flag_realloc_lhs
+	&& gfc_is_reallocatable_lhs (expr1)
+	&& !gfc_expr_attr (expr1).codimension
+	&& !gfc_is_coindexed (expr1)
+	&& !(expr2->value.function.esym
+	    && expr2->value.function.esym->result->attr.allocatable))
+    {
+      if (!expr2->value.function.isym)
+	{
+	  realloc_lhs_loop_for_fcn_call (&se, &expr1->where, &ss);
+	  ss->is_alloc_lhs = 1;
+	}
+      else
+	realloc_lhs_bounds_for_intrinsic_call (&se, expr1->rank);
+    }
+
   gfc_conv_function_expr (&se, expr2);
   gfc_add_block_to_block (&se.pre, &se.post);
 
@@ -5603,6 +5751,10 @@ gfc_trans_assignment_1 (gfc_expr * expr1, gfc_expr * expr2, bool init_flag,
 
   /* Walk the lhs.  */
   lss = gfc_walk_expr (expr1);
+  if (gfc_is_reallocatable_lhs (expr1)
+	&& !(expr2->expr_type == EXPR_FUNCTION
+	     && expr2->value.function.isym != NULL))
+    lss->is_alloc_lhs = 1;
   rss = NULL;
   if (lss != gfc_ss_terminator)
     {
@@ -5748,6 +5900,17 @@ gfc_trans_assignment_1 (gfc_expr * expr1, gfc_expr * expr2, bool init_flag,
 	  gfc_add_expr_to_block (&body, tmp);
 	}
 
+      /* Allocate or reallocate lhs of allocatable array.  */
+      if (gfc_option.flag_realloc_lhs
+	    && gfc_is_reallocatable_lhs (expr1)
+	    && !gfc_expr_attr (expr1).codimension
+	    && !gfc_is_coindexed (expr1))
+	{
+	  tmp = gfc_alloc_allocatable_for_assignment (&loop, expr1, expr2);
+	  if (tmp != NULL_TREE)
+	    gfc_add_expr_to_block (&loop.code[expr1->rank - 1], tmp);
+	}
+
       /* Generate the copying loops.  */
       gfc_trans_scalarizing_loops (&loop, &body);